adding another disc to a R80 G/S

[One Less Harley]

Caddy, where did you get the kit??? or what parts..

[Caddy82rats]

Originally Posted by One Less Harley

Caddy, where did you get the kit??? or what parts..

SEMC is Brembo provider

http://www.semc-brembo.com/en/

here you've got an adress in Quebec

http://www.semc-brembo.com/en/wheretobuy.php

but this is a factory hub same disc mesurement (diferent ofset)
If you need it, I can take some mesurements on my bike (and if it's not raining tomorow !)

[One Less Harley]

Don't worry about the mesurement. Did you pit the kit on the bike? The disc looks different than stock.
I'm thinking the offset is handled by the axle spacers and not the off set of the hub to rim

[Rucksta]

Guys

The trick to the twin disc settup is in the disc carrier. Single discs use a deep carrier twin discs use a shallow carrier this is what gives the wheel centering and spacing. A bit of mucking around with the wedding band and axle spacer may be required .
A small flat may need to be machined into the left fork leg to clear the rivets but if you are recycling your disc(s) to a shallow carrier, attachment with coutersunk screws instead of rivets will prevent the need to do this.
Triple clamps are same spec (apart from 6 holes on the G/S).
A left side caliper a t-piece extra hoses, mounting hardware and a larger bore master cylinder are of course required.

Results obtained with a 300mm disc conversion are said by some to be superior to a twin disc conversion.

Sorry no pics I went for a nissan twin spot caliper and braided line.

[One Less Harley]

Rucksta that's what i was thinking!!!!


I thought this kit would work, but motobin said no, I still think it would, just some little mods, unless the calipers are for the front of the forks
http://www.motobins.co.uk/displayfin...ONOSHOCK+TWINS.

I'll just have to see about the 320mm disc conversion when it get here from across the pond. Stock caliper w/ EBC pads

[Rucksta]

One Less

That kit from motobins don't look right for a G/S or airhead with 36mm fork legs. The deal breaker would be the carriers have 4 holes not 5 for the mounting bolts.

The caliper in front of leg should not be an issue per see as you can swap left for right & visa versa. I think the mounting points were the same distance appart on the 85 on models butI have only eyeballed it and not measured.

I thought the 85 on only had mounting lugs on one fork leg but I'm not really into post 85. I would be suspisious of any kit that did not include a larger volume master cylinder.

[One Less Harley]

It would be possible (???)to use Motobins disc which are shallow disc p/n 20200G(five hole) and the Grimeca calipers (p/n's 20001G and 20002G), then figure out the plumbing (flex and hard lines, plus a"T" fitting) and change over the MC to a 14 or 15mm. Of course the spacing for the axle would need to be centered.

My '84 has mounting lugs on the left fork too.

Thanks for the input

[zenben]

Originally Posted by Rucksta

Guys

The trick to the twin disc settup is in the disc carrier. Single discs use a deep carrier twin discs use a shallow carrier this is what gives the wheel centering and spacing. A bit of mucking around with the wedding band and axle spacer may be required .
A small flat may need to be machined into the left fork leg to clear the rivets but if you are recycling your disc(s) to a shallow carrier, attachment with coutersunk screws instead of rivets will prevent the need to do this.
Triple clamps are same spec (apart from 6 holes on the G/S).
A left side caliper a t-piece extra hoses, mounting hardware and a larger bore master cylinder are of course required.

Results obtained with a 300mm disc conversion are said by some to be superior to a twin disc conversion.

Sorry no pics I went for a nissan twin spot caliper and braided line.

Yup, that's all correct. The G/S wheel is off center. To add the twin rotors, you'll need to re-space the wheel. I converted a G/S to dual rotors 20 years ago, and don't recall all the minutae in details, but it really isn't very difficult.
Larger M/C, discs, assorted shims/spacers, 2nd caliper, new lines.
In today's context, the 320 kit is probably a better solution.

[Caddy82rats]

Originally Posted by One Less Harley

Don't worry about the mesurement. Did you pit the kit on the bike? The disc looks different than stock.
I'm thinking the offset is handled by the axle spacers and not the off set of the hub to rim

Yes i've put the kit on the bike
2 Wheeel spacer (to put it perfectly at the midle of the fork)
4 spacers to put the calipiers outer (around 2mm)
2 calipiers (smaler bores I presume)
1 "T" for break line
1 line
1 BMW handlebar pump 15 or 14mm I don't remember
2 disc (cast one perfectly flat) billet carrier for the disc (Stamped SEMC Brembo)
2 calipier bolts (Seems to be OEM BMW)

I've buy the bike with 2 box of parts, that kit, spare parts, 3 box Lugage kit, tachometer kit, OEM windshield, etc

I thing that a 4 pot R100R calipier is direct bolt on upgrade

For me the good points of twin disc :
- You center the wheel in the fork
- The fork doesn't flex one side when you break
- Easy to find aftemarket disc as it's same spec than OEM (SEMC had them bolted to the carrier).

[Caddy82rats]

Originally Posted by SOLO LOBO

TEXASYETI's G/S came to him with dual discs... let's see what he can add to this discussion

PS : Solo Lobo :
I've read your post about silencer
Any apdate about your G/S rebuild ?

[SOLO LOBO]

Originally Posted by Caddy82rats

PS : Solo Lobo :
I've read your post about silencer
Any apdate about your G/S rebuild ?

Well, rode in today to work and that's about as far I have gotten recently....

[batoutoflahonda]

I'd be happy if i could figure my stock ones out. If the L/H cinch bolt on the lower fork leg isn't tightened first, the rivets from the rotor rub on the R/H fork leg. Some where along the 28 years of it's life some one swapped out the caliper mounting bolts with good 'ol grade 8 hex heads, too long of course, and used washers between the fork and caliper to center things up. If you take it apart and don't stack the washers up right, 3 under the lower bolt head, two under the upper, two on the caliper mounts. Fine tuning and Perfectly safe to be sure.

Looking at the Max parts fish, there are spacers between the caliper mounts and forks on the G/S. Any of you G/S owners have spacers between the caliper and fork leg?

[SOLO LOBO]

Originally Posted by batoutoflahonda

and used washers between the fork and caliper to center things up.

The thick washers between the caliper and fork leg mounts are stock pieces...

Looks like you could pull these, shorten the spacers and shift the wheel to the right a bit easily... wonder if that is how you get the second disc to work?

[batoutoflahonda]

Originally Posted by SOLO LOBO

The thick washers between the caliper and fork leg mounts are stock pieces...

Looks like you could pull these, shorten the spacers and shift the wheel to the right a bit easily... wonder if that is how you get the second disc to work?

Ok thanks. Not sure if you can move it over to the right. The rivets on the rotor barly clear the fork leg on mine. Unless, some one was trying to go to dual roters on mine and shortened the spacer. I'll measure them next time I have it apart and let you all know.

I'll be pulling the fender and split washers/with the grade 8 bolt mod. If any one wants to trick their bike out and add a bling bling I'll sell you the slightly used kit for $5.00 + $25.00 shipping and handling. USD. No low ballers!

[Wirespokes]

I've been taking a good look at this situation recently, but from a different angle. I've got an 84 R100 I want to convert from snowflakes to wires, like the R100CS. The 81-4 R100 front end is practically the same as the G/S with a few minor differences - the damping mechanism internally and notches in the sliders for brake disc clearance.

So I've been doing a bit of measuring and comparing to figure out how the factory fit the wire wheel and two discs into that space, and got the calipers to work. With that data I can now supply some figures to help you mount dual discs on the G/S

One thing they did with the CS that you most likely won't be doing is make the hub 5mm narrower. That was just enough to allow 2mm clearance between each disc and it's slider. The calipers were then moved 5mm further out with spacers.

The trick with the stock G/S wheel is to either narrow the hub or shave some material from the mounting area of the disc. Measure the distance you have to work with: between the sliders = 137mm. G/S wheel disc to disc (outside edge to outside edge of each) = 137mm.

You see, something's gotta give - forks gotta get wider or, hub's gotta get narrower, or, disc's gotta get narrower.

Those are the only options. Measure your clearance on the G/S - disc to slider. On mine it was close to 2mm. There you have it - all the data you need to figure this thing out!

And of course remove the offset from the wheel, and rig up all the proper spacers to align the whole mess.